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Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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16 pages, 2505 KiB  
Article
TRNSYS Simulation of a Bi-Functional Solar-Thermal-Energy-Storage-Assisted Heat Pump System
by Mingzhen Wang, Eric Hu and Lei Chen
Energies 2024, 17(14), 3376; https://doi.org/10.3390/en17143376 - 10 Jul 2024
Cited by 3 | Viewed by 1361
Abstract
The escalating energy demands in buildings, particularly for heating and cooling demands met by heat pumps, have placed a growing stress on energy resources. The bi-functional thermal diode tank (BTDT) is proposed as thermal energy storage to improve the heating and cooling performances [...] Read more.
The escalating energy demands in buildings, particularly for heating and cooling demands met by heat pumps, have placed a growing stress on energy resources. The bi-functional thermal diode tank (BTDT) is proposed as thermal energy storage to improve the heating and cooling performances of heat pumps in both summer and winter. The BTDT is an insulated water tank with a gravity heat pipe (GHP), which can harvest and store heat passively from sun radiation and the external environment during the daytime. In summer, it harvests and stores cold energy from the air and night sky during the daytime. The performance of the BTDT-assisted heat pump (BTDT-HP) system in Adelaide, Australia, during the 2021–2022 summer and winter seasons was evaluated by conducting a TRNSYS simulation. This study revealed that the BTDT-HP system outperformed the reference ASHP system, where up to 8% energy in heating and 39.75% energy in cooling could be saved. An overall reduction in the energy consumption of 18.89% was achieved. Increasing the BTDT volume and GHP panel area enabled the tank to store more thermal and cold energy across the winter and summer seasons, thereby improving the system’s performance. The maximum ESPs were found to be 31.6% and 41.2% for heating and cooling for the study case under optimal conditions. When the GHP panel area was fixed at 15 m2, the BTDT volume should be at least 28 m3 for the BTDT-HP system, boasting cooling and heating capacities of 40 kW and 43.2 kW, to achieve positive energy savings. Full article
(This article belongs to the Section A2: Solar Energy and Photovoltaic Systems)
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19 pages, 1292 KiB  
Article
Facilitating a Sustainable Aviation Fuel Transition in Italy
by Riccardo Erriu, Edoardo Marcucci and Valerio Gatta
Energies 2024, 17(14), 3388; https://doi.org/10.3390/en17143388 - 10 Jul 2024
Cited by 1 | Viewed by 1797
Abstract
Civil aviation significantly contributes to “hard-to-abate” emissions, responsible for 2% of global CO2 emissions. This paper examines the most effective policies to promote Sustainable Aviation Fuels (SAFs) in Italy, using a multi-level policy analysis and a stakeholder-based case study approach. The policies [...] Read more.
Civil aviation significantly contributes to “hard-to-abate” emissions, responsible for 2% of global CO2 emissions. This paper examines the most effective policies to promote Sustainable Aviation Fuels (SAFs) in Italy, using a multi-level policy analysis and a stakeholder-based case study approach. The policies reviewed comprise the international, European, and national level. The paper analyses at the international level, ICAO CORSIA and, at the European level, the Renewable Energy Directive (RED), ReFuel EU, and the EU Emissions Trading System (EU ETS) for aviation. Italy has not yet implemented specific policies targeting SAF transition, which is challenging due to commercialization issues and policy inconsistencies. These include the price gap between SAF and conventional fuels, different definitions adopted, and environmental objectives pursued with respect to sustainable fuels by ICAO and the EU. Other challenges include double-counting risks and fuel tankering practices. This article contributes to Italy’s SAF policymaking by developing a stakeholder-based quantitative survey, whose results suggest that three measures are key: tax subsidies for technology and infrastructure users, tax credits for upgrading production infrastructure, and tax breaks for SAF-using companies, fuel handlers, and distributors. Full article
(This article belongs to the Section I1: Fuel)
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23 pages, 2181 KiB  
Article
The Role of Blockchain-Secured Digital Twins in Promoting Smart Energy Performance-Based Contracts for Buildings
by Mohamed Nour El-Din, João Poças Martins, Nuno M. M. Ramos and Pedro F. Pereira
Energies 2024, 17(14), 3392; https://doi.org/10.3390/en17143392 - 10 Jul 2024
Cited by 2 | Viewed by 1547
Abstract
Energy performance-based contracts (EPCs) offer a promising solution for enhancing the energy performance of buildings, which is an overarching step towards achieving Net Zero Carbon Buildings, addressing climate change and improving occupants’ comfort. Despite their potential, their execution is constrained by difficulties that [...] Read more.
Energy performance-based contracts (EPCs) offer a promising solution for enhancing the energy performance of buildings, which is an overarching step towards achieving Net Zero Carbon Buildings, addressing climate change and improving occupants’ comfort. Despite their potential, their execution is constrained by difficulties that hinder their diffusion in the architecture, engineering, construction, and operation industry. Notably, the Measurement and Verification process is considered a significant impediment due to data sharing, storage, and security challenges. Nevertheless, there have been minimal efforts to analyze research conducted in this field systematically. A systematic analysis of 113 identified journal articles was conducted to fill this gap. A paucity of research tackling the utilization of digital technologies to enhance the implementation of EPCs was found. Consequently, this article proposes a framework integrating Digital Twin and Blockchain technologies to provide an enhanced EPC execution environment. Digital Twin technology leverages the system by monitoring and evaluating energy performance in real-time, predicting future performance, and facilitating informed decisions. Blockchain technology ensures the integrity, transparency, and accountability of information. Moreover, a private Blockchain infrastructure was originally introduced in the framework to eliminate high transaction costs related to on-chain storage and potential concerns regarding the confidentiality of information in open distributed ledgers. Full article
(This article belongs to the Special Issue Solutions towards Zero Carbon Buildings)
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27 pages, 1106 KiB  
Article
Forecasting Electric Vehicles’ Charging Behavior at Charging Stations: A Data Science-Based Approach
by Herbert Amezquita, Cindy P. Guzman and Hugo Morais
Energies 2024, 17(14), 3396; https://doi.org/10.3390/en17143396 - 10 Jul 2024
Cited by 2 | Viewed by 1606
Abstract
The rising adoption of electric vehicles (EVs), driven by carbon neutrality goals, has prompted the need for accurate forecasting of EVs’ charging behavior. However, this task presents several challenges due to the dynamic nature of EVs’ usage patterns, including fluctuating demand and unpredictable [...] Read more.
The rising adoption of electric vehicles (EVs), driven by carbon neutrality goals, has prompted the need for accurate forecasting of EVs’ charging behavior. However, this task presents several challenges due to the dynamic nature of EVs’ usage patterns, including fluctuating demand and unpredictable charging durations. In response to these challenges and different from previous works, this paper presents a novel and holistic methodology for day-ahead forecasting of EVs’ plugged-in status and power consumption in charging stations (CSs). The proposed framework encompasses data analysis, pre-processing, feature engineering, feature selection, the use and comparison of diverse machine learning forecasting algorithms, and validation. A real-world dataset from a CS in Boulder City is employed to evaluate the framework’s effectiveness, and the results demonstrate its proficiency in predicting the EVs’ plugged-in status, with XGBoost’s classifier achieving remarkable accuracy with an F1-score of 0.97. Furthermore, an in-depth evaluation of six regression methods highlighted the supremacy of gradient boosting algorithms in forecasting the EVs’ power consumption, with LightGBM emerging as the most effective method due to its optimal balance between prediction accuracy with a 4.22% normalized root-mean-squared error (NRMSE) and computational efficiency with 5 s of execution time. The proposed framework equips power system operators with strategic tools to anticipate and adapt to the evolving EV landscape. Full article
(This article belongs to the Topic Smart Energy Systems, 2nd Edition)
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19 pages, 811 KiB  
Article
Does Crime Influence Investment in Renewable Energy Sources? Empirical Evidence from Italy
by Giuseppe Scandurra, Alfonso Carfora and Antonio Thomas
Energies 2024, 17(14), 3393; https://doi.org/10.3390/en17143393 - 10 Jul 2024
Cited by 3 | Viewed by 1059
Abstract
The Sustainable Development Goals are significantly increasing investments in the production of energy from renewable sources (RESs). To this end, the supply of monetary incentives by public institutions has increased sharply. This flow of money inevitably attracts the attention of criminal organizations (henceforth [...] Read more.
The Sustainable Development Goals are significantly increasing investments in the production of energy from renewable sources (RESs). To this end, the supply of monetary incentives by public institutions has increased sharply. This flow of money inevitably attracts the attention of criminal organizations (henceforth COs) that use their power to increase the volumes of investments, while public authorities might react by deciding not to make investments in RESs in areas at risk of distorted use of incentives. In this context, the research question is as follows: does the presence of COs slow down or encourage investment in RESs? Until now, this topic has received little attention from researchers, at least in the European Union. In particular, the presence of COs is particularly pervasive in the economic system of Italy. Given the heterogeneity of this country, a spatial econometric approach was used, taking into account geographical dependency relationships and their impact on the relevant variables. The main result of the research shows a negative relationship between Italian areas with higher CO levels and RES investments. In other words, investments are discouraged in these regions. This situation is detrimental to the target regions in terms of sustainable development and increasing the gross national product (GNP). Furthermore, we found that micro-crime cannot in any way influence investments in RESs. Full article
(This article belongs to the Section B: Energy and Environment)
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16 pages, 3507 KiB  
Article
Influence of Performance Packages on Fuel Consumption and Exhaust Emissions of Passenger Cars and Commercial Vehicles under WLTP
by Luca Marchitto, Maria Antonietta Costagliola and Alessandra Berra
Energies 2024, 17(14), 3356; https://doi.org/10.3390/en17143356 - 9 Jul 2024
Cited by 2 | Viewed by 1386
Abstract
The transportation sector is responsible for about 16% of worldwide greenhouse gas emissions. Despite efforts for a sensible reduction by means of new technologies’ development, the average age of a vehicle fleet is 12.3 years in the European Union. In light of this, [...] Read more.
The transportation sector is responsible for about 16% of worldwide greenhouse gas emissions. Despite efforts for a sensible reduction by means of new technologies’ development, the average age of a vehicle fleet is 12.3 years in the European Union. In light of this, actions aiming at improving the efficiency of circulating vehicles can prove effective in the short to mid-term. Introducing performance packages in standard fuels could allow a reduction in the CO2 emissions of whole vehicle fleets without any modification to powertrain. Such a kind of additive is generally used in premium fuels; deposit control additives can reduce or control the deposits at intake valves and at nozzle holes with benefits for the fuel efficiency and exhaust emissions. Further improvements in combustion phasing can be achieved with cetane/octane improver. This paper aims to assess the influence of two performance packages on the exhaust emissions and fuel consumption of five vehicles set to be as representative as possible of circulating Italian passenger cars and light commercial fleet vehicles (LCVs). Based on the literature datasets, three Euro 4 vehicles were selected with a mileage representative of each single vehicle class: two passenger cars (one spark ignition and one diesel) and an LCV. Further, two diesel Euro 6 vehicles, a passenger car and an LCV, were tested to investigate the effect of fuel additives on the combustion of vehicles compliant with current homologation regulation. Exhaust emissions and fuel consumption were experimentally estimated on a chassis dynamometer over a worldwide harmonized light vehicles test cycle (WLTC) in a climate-controlled laboratory. Each vehicle was preliminarily tested when running with base fuel, then a 3000 km clean-up stage was performed using the additive package. Finally, WLTC tests were repeated. Results demonstrated the efficiency of the performance packages with a reduction between 1.2% (diesel Euro 6 passenger car) and 8.1% (diesel Euro 4 passenger car) in fuel consumption. Similar trends were found for CO2 emissions. Further, a sensible reduction in THCs, CO and PM was found for each vehicle class. Full article
(This article belongs to the Special Issue New Fuels and Advanced Combustion Modes for Innovative Internal Combustion Engines)
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31 pages, 9721 KiB  
Review
Solar Window Innovations: Enhancing Building Performance through Advanced Technologies
by Mehrdad Ghamari and Senthilarasu Sundaram
Energies 2024, 17(14), 3369; https://doi.org/10.3390/en17143369 - 9 Jul 2024
Cited by 6 | Viewed by 2573
Abstract
Building-integrated photovoltaic (BIPV) glazing systems with intelligent window technologies enhance building energy efficiency by generating electricity and managing daylighting. This study explores advanced BIPV glazing, focusing on building-integrated concentrating photovoltaic (BICPV) systems. BICPV integrates concentrating optics, such as holographic films, luminescent solar concentrators [...] Read more.
Building-integrated photovoltaic (BIPV) glazing systems with intelligent window technologies enhance building energy efficiency by generating electricity and managing daylighting. This study explores advanced BIPV glazing, focusing on building-integrated concentrating photovoltaic (BICPV) systems. BICPV integrates concentrating optics, such as holographic films, luminescent solar concentrators (LSC), Fresnel lenses, and compound parabolic concentrators (CPCs), with photovoltaic cells. Notable results include achieving 17.9% electrical efficiency using cylindrical holographic optical elements and crystalline silicon cells at a 3.5× concentration ratio. Dielectric CPCs showed 97.7% angular acceptance efficiency in simulations and 94.4% experimentally, increasing short-circuit current and maximum power by 87.0% and 96.6%, respectively, across 0° to 85° incidence angles. Thermochromic hydrogels and thermotropic smart glazing systems demonstrated significant HVAC energy savings. Large-area 1 m2 PNIPAm-based thermotropic window outperformed conventional double glazing in Singapore. The thermotropic parallel slat transparent insulation material (TT PS-TIM) improved energy efficiency by up to 21.5% compared to double glazing in climates like London and Rome. Emerging dynamic glazing technologies combine BIPV with smart functions, balancing transparency and efficiency. Photothermally controlled methylammonium lead iodide PV windows achieved 68% visible light transmission, 11.3% power conversion efficiency, and quick switching in under 3 min. Polymer-dispersed liquid crystal smart windows provided 41–68% visible transmission with self-powered operation. Full article
(This article belongs to the Collection Featured Papers in Solar Energy and Photovoltaic Systems Section)
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14 pages, 4451 KiB  
Article
Application of Silver Nanoparticles Supported over Mesoporous Carbon Produced from Sustainable Sources as Catalysts for Hydrogen Production
by Erik Biehler, Qui Quach and Tarek M. Abdel-Fattah
Energies 2024, 17(13), 3327; https://doi.org/10.3390/en17133327 - 7 Jul 2024
Cited by 1 | Viewed by 1298
Abstract
The growing population and increasingly competitive economic climate have increased the demand for alternative fuel sources, with hydrogen being one of the more viable options. Many metal hydrides, including sodium borohydride, are capable of releasing hydrogen stored within chemical bonds when reacted with [...] Read more.
The growing population and increasingly competitive economic climate have increased the demand for alternative fuel sources, with hydrogen being one of the more viable options. Many metal hydrides, including sodium borohydride, are capable of releasing hydrogen stored within chemical bonds when reacted with water, but the rate of generation is slow and therefore necessitates a catalyst. Silver nanoparticles, which were chosen due to their known catalytic activity, were synthesized from sodium citrate and were embedded in mesoporous carbon to form a nano-composite catalyst (Ag-MCM). This composite was characterized via Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), and Scanning Electron Microscopy/Energy-Dispersive X-ray Spectroscopy (SEM/EDS). Catalytic testing showed that the catalytic activity for the Ag-MCM catalyst increased with increasing NaBH4 concentration, low pH, and high temperatures. The Ag-MCM catalyst resulted in the activation energy at 15.6 kJ mol−1, making it one of the lowest seen activation energies for inorganic catalysts. Lastly, the Ag-MCM catalysts showed stability, producing, on average, 20.0 mL per trial for five consecutive trials. This catalytic ability along with the cheap, carbon-based backbone that is made from readily available corn starch, makes it a promising catalyst for the hydrolysis of NaBH4. Full article
(This article belongs to the Special Issue Element 1 for Sustainable Decarbonization and Net-Zero Economy: Progress in Generation, Storage, Distribution and End-Use Technologies)
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27 pages, 4692 KiB  
Article
Decarbonization through Active Participation of the Demand Side in Relatively Isolated Power Systems
by Sophie Chlela, Sandrine Selosse and Nadia Maïzi
Energies 2024, 17(13), 3328; https://doi.org/10.3390/en17133328 - 7 Jul 2024
Viewed by 1407
Abstract
In the context of power system decarbonization, the demand-side strategy for increasing the share of renewable energy is studied for two constrained energy systems. This strategy, which is currently widely suggested in policies on the energy transition, would impact consumer behavior. Despite the [...] Read more.
In the context of power system decarbonization, the demand-side strategy for increasing the share of renewable energy is studied for two constrained energy systems. This strategy, which is currently widely suggested in policies on the energy transition, would impact consumer behavior. Despite the importance of studying the latter, the focus here is on decisions regarding the type, location, and timeframe of implementing the related measures. As such, solutions must be assessed in terms of cost and feasibility, technological learning, and by considering geographical and environmental constraints. Based on techno-economic optimization, in this paper we analyze the evolution of the power system and elaborate plausible long-term trajectories in the energy systems of two European islands. The case studies, Procida in Italy and Hinnøya in Norway, are both electrically connected to the mainland by submarine cables and present issues in their power systems, which are here understood as relatively isolated power systems. Renewable energy integration is encouraged by legislative measures in Italy. Although not modeled here, they serve as a backbone for the assumptions of increasing these investments. For Procida, rooftop photovoltaics (PV) coupled with energy storage are integrated in the residential, public, and tertiary sectors. A price-based strategy is also applied reflecting the Italian electricity tariff structure. At a certain price difference between peak and off-peak, the electricity supply mix changes, favoring storage technologies and hence decreasing imports by up to 10% during peak times in the year 2050. In Norway, renewable energy resources are abundant. The analysis for Hinnøya showcases possible cross-sectoral flexibilities through electrification, leading to decarbonization. By fine-tuning electric vehicle charging tactics and leveraging Norway’s electricity pricing model, excess electricity demand peaks can be averted. The conclusions of this double-prospective study provide a comparative analysis that presents the lessons learnt and makes replicability recommendations for other territories. Full article
(This article belongs to the Special Issue Optimal Planning and Operation in RES-Rich Power Systems under Electricity and Carbon Emission Market Environment)
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25 pages, 13011 KiB  
Article
A New Torque Control Approach for Torque Ripple Minimisation in Switched Reluctance Drives
by Ali Abdel-Aziz, Mohamed Elgenedy and Barry Williams
Energies 2024, 17(13), 3334; https://doi.org/10.3390/en17133334 - 7 Jul 2024
Cited by 1 | Viewed by 1724
Abstract
The switched reluctance motor (SRM) has many merits, such as robustness, a simple construction, low cost, and no permanent magnets. However, its deployment in servo applications is restrained due to acoustic noise and torque ripple (TR). This paper presents a new torque control [...] Read more.
The switched reluctance motor (SRM) has many merits, such as robustness, a simple construction, low cost, and no permanent magnets. However, its deployment in servo applications is restrained due to acoustic noise and torque ripple (TR). This paper presents a new torque control approach for TR reduction in switched reluctance drives. The approach is based on the maximum utilisation of the available dc-link voltage, hence extending the zero torque-ripple speed range. The approach is suitable for an SRM with any number of phases and stator/rotor poles. Soft switching control is deployed, which reduces switching losses. At any instant (regardless of the number of phases being conducted simultaneously), only one phase current is controlled. The well-established torque-sharing function concept is adapted and generalised to cater for more than two phases conducting simultaneously. MATLAB/Simulink confirmation simulations are based on the widely studied four-phase 8/6, 4 kW, 1500 rpm SRM. Full article
(This article belongs to the Section E: Electric Vehicles)
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19 pages, 321 KiB  
Article
Sustainable Energy Sources and Financial Development Nexus—Perspective of European Union Countries in 2013–2021
by Magdalena Zioło, Iwona Bąk and Anna Spoz
Energies 2024, 17(13), 3332; https://doi.org/10.3390/en17133332 - 7 Jul 2024
Cited by 5 | Viewed by 1880
Abstract
The focus of this paper is the relationship between sustainable energy sources and financial development. The main research hypothesis assumes a positive link between these areas, with inevitable differences across countries and business sectors. The following research questions were asked: Is the impact [...] Read more.
The focus of this paper is the relationship between sustainable energy sources and financial development. The main research hypothesis assumes a positive link between these areas, with inevitable differences across countries and business sectors. The following research questions were asked: Is the impact of financial development on sustainable energy resources the same in different EU countries advanced in green transition processes? How is transition towards renewable energy sources progressing in different economic sectors? Does financial development influence sectoral transition in particular countries? This study uses the TOPSIS method and 25 variables for EU countries from 2013 to 2021. Key findings reveal that the link between sustainable energy sources and financial development varies across EU countries, country size affects energy autonomy, and the transition also differs by business sector. Surprisingly, higher financial development correlates with less progress in sustainable energy initiatives. The results of our research may be useful for government decision-makers in the process of designing and controlling the country’s transition to sustainable energy. The original contribution of the study is expressed in its the diagnosis of the relationship between financial development and sustainable energy sources, while most studies have focused on the relationship between the energy market and financial development. Full article
(This article belongs to the Special Issue Breakthroughs in Sustainable Energy and Economic Development)
24 pages, 4954 KiB  
Review
Wireless Battery Management Systems: Innovations, Challenges, and Future Perspectives
by Zhi Cao, Wei Gao, Yuhong Fu and Chris Mi
Energies 2024, 17(13), 3277; https://doi.org/10.3390/en17133277 - 4 Jul 2024
Cited by 7 | Viewed by 5313
Abstract
With the growing adoption of battery energy storage systems in renewable energy sources, electric vehicles (EVs), and portable electronic devices, the effective management of battery systems has become increasingly critical. The advent of wireless battery management systems (wBMSs) represents a significant innovation in [...] Read more.
With the growing adoption of battery energy storage systems in renewable energy sources, electric vehicles (EVs), and portable electronic devices, the effective management of battery systems has become increasingly critical. The advent of wireless battery management systems (wBMSs) represents a significant innovation in battery management technology. Traditional wired battery management systems (BMSs) face challenges, including complexity, increased weight, maintenance difficulties, and a higher chance of connection failure. In contrast, wBMSs offer a robust solution, eliminating physical connections. wBMSs offer enhanced flexibility, reduced packaging complexity, and improved reliability. Given that wBMSs are still in a preliminary stage, this review paper explores their evolution, current state, and future directions. A comprehensive survey of state-of-the-art wBMS technologies, including academic and commercial solutions, is elaborated in this paper. We compare wireless communication technologies like Bluetooth Low Energy (BLE), Zigbee, Near-Field Communication (NFC), Wi-Fi, and cellular networks in the context of wBMSs. We discuss their performance in terms of efficiency, reliability, scalability, and security. Despite its promising outlook, wBMSs still face challenges such as data security, signal interference, regulatory and standardization issues, and competition from the continued advancement of wired BMS technologies, making the advantages of wBMSs less evident. This paper concludes with guidelines for future research and development of wBMSs, aiming to address these challenges and pave the way for a broad adoption of wBMSs across various applications. This paper aims to inspire further research and innovation in the field, contributing to developing an industry-ready wBMS. Full article
(This article belongs to the Section F: Electrical Engineering)
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23 pages, 654 KiB  
Review
Strengthening Power Systems for Net Zero: A Review of the Role of Synchronous Condensers and Emerging Challenges
by Hamid Soleimani, Daryoush Habibi, Mehrdad Ghahramani and Asma Aziz
Energies 2024, 17(13), 3291; https://doi.org/10.3390/en17133291 - 4 Jul 2024
Cited by 7 | Viewed by 2566
Abstract
System strength is both supplied and demanded in a power system during normal operations and in the presence of disturbances. This is characterised by stable voltage and frequency, supporting renewable generation such as wind and solar. Because the retirement of synchronous generators reduces [...] Read more.
System strength is both supplied and demanded in a power system during normal operations and in the presence of disturbances. This is characterised by stable voltage and frequency, supporting renewable generation such as wind and solar. Because the retirement of synchronous generators reduces system strength supply, and the connection of new inverter-based resource (IBR) generators increases demand, there is an urgent need for new sources of system strength. This paper provides an overview of the challenges brought about by grid modernisation. It highlights tangible solutions provided by synchronous condensers (SCs) to bolster grid strength, stability, and reliability while accommodating the rising influx of renewable energy sources (RESs). Furthermore, this paper examines the role of SCs in improving weak grids, voltage control, power quality, short-circuit levels, and inertia management. It introduces the role of innovative hybrid synchronous condenser (HSC) systems to boost grid reliability and resilience. It also elaborates on the optimisation strategies for SC sizing, placement, and control and outlines economic aspects of their deployment. The review also highlights future directions and challenges in SC technology, emphasising the need for ongoing research and development to enhance system design and operation. Full article
(This article belongs to the Special Issue Computational Intelligence-Based Modeling, Control, Estimation, and Optimization in Electrical Motor/Drive, Renewable Energy, and Power Systems, Volume II)
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24 pages, 11723 KiB  
Article
Energy Consumption and Saved Emissions of a Hydrogen Power System for Ultralight Aviation: A Case Study
by Teresa Donateo, Andrea Graziano Bonatesta, Antonio Ficarella and Leonardo Lecce
Energies 2024, 17(13), 3272; https://doi.org/10.3390/en17133272 - 3 Jul 2024
Cited by 1 | Viewed by 1588
Abstract
The growing concern about climate change and the contemporary increase in mobility requirements call for faster, cheaper, safer, and cleaner means of transportation. The retrofitting of fossil-fueled piston engine ultralight aerial vehicles to hydrogen power systems is an option recently proposed in this [...] Read more.
The growing concern about climate change and the contemporary increase in mobility requirements call for faster, cheaper, safer, and cleaner means of transportation. The retrofitting of fossil-fueled piston engine ultralight aerial vehicles to hydrogen power systems is an option recently proposed in this direction. The goal of this investigation is a comparative analysis of the environmental impact of conventional and hydrogen-based propulsive systems. As a case study, a hybrid electric configuration consisting of a fuel cell with a nominal power of about 30 kW, a 6 kWh LFP battery, and a pressurized hydrogen vessel is proposed to replace a piston prop configuration for an ultralight aerial vehicle. Both power systems are modeled with a backward approach that allows the efficiency of the main components to be evaluated based on the load and altitude at every moment of the flight with a time step of 1 s. A typical 90 min flight mission is considered for the comparative analysis, which is performed in terms of direct and indirect emissions of carbon dioxide, water, and pollutant substances. For the hydrogen-based configuration, two possible strategies are adopted for the use of the battery: charge sustaining and charge depleting. Moreover, the effect of the altitude on the parasitic power of the fuel cell compressor and, consequently, on the net efficiency of the fuel cell system is taken into account. The results showed that even if the use of hydrogen confines the direct environmental impact to the emission of water (in a similar quantity to the fossil fuel case), the indirect emissions associated with the production, transportation, and delivery of hydrogen and electricity compromise the desired achievement of pollutant-free propulsion in terms of equivalent emissions of CO2 and VOCs if hydrogen is obtained from natural gas reforming. However, in the case of green hydrogen from electrolysis with wind energy, the total (direct and indirect) emissions of CO2 can be reduced up to 1/5 of the fossil fuel case. The proposed configuration has the additional advantage of eliminating the problem of lead, which is used as an additive in the AVGAS 100LL. Full article
(This article belongs to the Section A5: Hydrogen Energy)
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31 pages, 1675 KiB  
Review
A Review of Edge Computing Technology and Its Applications in Power Systems
by Shiyang Liang, Shuangshuang Jin and Yousu Chen
Energies 2024, 17(13), 3230; https://doi.org/10.3390/en17133230 - 1 Jul 2024
Cited by 4 | Viewed by 4384
Abstract
Recent advancements in network-connected devices have led to a rapid increase in the deployment of smart devices and enhanced grid connectivity, resulting in a surge in data generation and expanded deployment to the edge of systems. Classic cloud computing infrastructures are increasingly challenged [...] Read more.
Recent advancements in network-connected devices have led to a rapid increase in the deployment of smart devices and enhanced grid connectivity, resulting in a surge in data generation and expanded deployment to the edge of systems. Classic cloud computing infrastructures are increasingly challenged by the demands for large bandwidth, low latency, fast response speed, and strong security. Therefore, edge computing has emerged as a critical technology to address these challenges, gaining widespread adoption across various sectors. This paper introduces the advent and capabilities of edge computing, reviews its state-of-the-art architectural advancements, and explores its communication techniques. A comprehensive analysis of edge computing technologies is also presented. Furthermore, this paper highlights the transformative role of edge computing in various areas, particularly emphasizing its role in power systems. It summarizes edge computing applications in power systems that are oriented from the architectures, such as power system monitoring, smart meter management, data collection and analysis, resource management, etc. Additionally, the paper discusses the future opportunities of edge computing in enhancing power system applications. Full article
(This article belongs to the Collection Review Papers on Electrical Power and Energy System)
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14 pages, 5389 KiB  
Article
Two-Phase Cooling System for Electric Vehicle Battery Based on a 3D Pulsating Heat Pipe
by Luca Cattani, Matteo Malavasi, Fabio Bozzoli, Valerio D’Alessandro and Luca Giammichele
Energies 2024, 17(13), 3236; https://doi.org/10.3390/en17133236 - 1 Jul 2024
Cited by 5 | Viewed by 1714
Abstract
The primary objective pursued in this research is the creation and thorough evaluation of an inventive cooling system designed to uphold optimal temperatures within the batteries employed in electric vehicles. Nowadays, the prevailing equipment underpinning electrical motion hinges on Lithium-Ion cells. These cells [...] Read more.
The primary objective pursued in this research is the creation and thorough evaluation of an inventive cooling system designed to uphold optimal temperatures within the batteries employed in electric vehicles. Nowadays, the prevailing equipment underpinning electrical motion hinges on Lithium-Ion cells. These cells frequently necessitate the expeditious delivery of substantial power, thereby giving rise to a consequential generation of heat. Consequently, there is an emergence of elevated operational temperatures, potentially causing noteworthy declines in battery performance, or, in extreme cases, operational failures. Furthermore, deviating from the recommended temperature range (20–40 °C) significantly expedites the aging process of the battery and elevates the probability of premature malfunction. In response to these crucial challenges, the implementation of a battery thermal management system assumes a pivotal role in maximizing battery efficiency. Within the framework of this investigation, we propose the adoption of a cooling system founded on a three-dimensional pulsating heat pipe as the designated thermal management technology for a battery pack. The preliminary phase of our study involved the assessment of the suggested pulsating heat pipe’s performance. Following this, the efficacy of the pulsating heat pipe is subjected to rigorous scrutiny through practical experimentation on an authentic electric battery. The empirical findings conclusively highlight the substantial cooling capacity of the proposed system, thereby presenting a robust and efficacious solution for the thermal management challenges faced by electric vehicle batteries. Full article
(This article belongs to the Topic Advanced Battery Thermal Management Solution for Electric Vehicles)
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17 pages, 1139 KiB  
Article
Constructing Interval Forecasts for Solar and Wind Energy Using Quantile Regression, ARCH and Exponential Smoothing Methods
by John Boland
Energies 2024, 17(13), 3240; https://doi.org/10.3390/en17133240 - 1 Jul 2024
Cited by 3 | Viewed by 1138
Abstract
The research reported in this article focuses on a comparison of two different approaches to setting error bounds, or prediction intervals, on short-term forecasting of solar irradiation as well as solar and wind farm output. Short term in this instance relates to the [...] Read more.
The research reported in this article focuses on a comparison of two different approaches to setting error bounds, or prediction intervals, on short-term forecasting of solar irradiation as well as solar and wind farm output. Short term in this instance relates to the time scales applicable in the Australian National Electricity Market (NEM), which operates on a five-minute basis throughout the year. The Australian Energy Market Operator (AEMO) has decided in recent years that, as well as point forecasts of energy, it is advantageous for planning purposes to have error bounds on those forecasts. We use quantile regression as one of the techniques to construct the bounds. This procedure is compared to a method of forecasting the conditional variance by use of either ARCH/GARCH or exponential smoothing, whichever is more appropriate for the specific application. The noise terms for these techniques must undergo a normalising transformation before their application. It seems that, for certain applications, quantile regression performs better, and the other technique for some other applications. Full article
(This article belongs to the Special Issue Volume Ⅱ: Advances in Wind and Solar Farm Forecasting)
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25 pages, 6356 KiB  
Article
Techno-Economic Analysis of Clean Hydrogen Production Plants in Sicily: Comparison of Distributed and Centralized Production
by Fabio Massaro, Marco Ferraro, Francesco Montana, Eleonora Riva Sanseverino and Salvatore Ruffino
Energies 2024, 17(13), 3239; https://doi.org/10.3390/en17133239 - 1 Jul 2024
Cited by 1 | Viewed by 1972
Abstract
This paper presents an assessment of the levelized cost of clean hydrogen produced in Sicily, a region in Southern Italy particularly rich in renewable energy and where nearly 50% of Italy’s refineries are located, making a comparison between on-site production, that is, near [...] Read more.
This paper presents an assessment of the levelized cost of clean hydrogen produced in Sicily, a region in Southern Italy particularly rich in renewable energy and where nearly 50% of Italy’s refineries are located, making a comparison between on-site production, that is, near the end users who will use the hydrogen, and centralized production, comparing the costs obtained by employing the two types of electrolyzers already commercially available. In the study for centralized production, the scale factor method was applied on the costs of electrolyzers, and the optimal transport modes were considered based on the distance and amount of hydrogen to be transported. The results obtained indicate higher prices for hydrogen produced locally (from about 7 €/kg to 10 €/kg) and lower prices (from 2.66 €/kg to 5.80 €/kg) for hydrogen produced in centralized plants due to economies of scale and higher conversion efficiencies. How-ever, meeting the demand for clean hydrogen at minimal cost requires hydrogen distribution pipelines to transport it from centralized production sites to users, which currently do not exist in Sicily, as well as a significant amount of renewable energy ranging from 1.4 to 1.7 TWh per year to cover only 16% of refineries’ hydrogen needs. Full article
(This article belongs to the Special Issue Advances in Hydrogen Energy III)
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24 pages, 2243 KiB  
Article
Energy Consumption Prediction in Residential Buildings—An Accurate and Interpretable Machine Learning Approach Combining Fuzzy Systems with Evolutionary Optimization
by Marian B. Gorzałczany and Filip Rudziński
Energies 2024, 17(13), 3242; https://doi.org/10.3390/en17133242 - 1 Jul 2024
Cited by 3 | Viewed by 1684
Abstract
This paper addresses the problem of accurate and interpretable prediction of energy consumption in residential buildings. The solution that we propose in this work employs the knowledge discovery machine learning approach combining fuzzy systems with evolutionary optimization. The contribution of this work is [...] Read more.
This paper addresses the problem of accurate and interpretable prediction of energy consumption in residential buildings. The solution that we propose in this work employs the knowledge discovery machine learning approach combining fuzzy systems with evolutionary optimization. The contribution of this work is twofold, including both methodology and experimental investigations. As far as methodological contribution is concerned, in this paper, we present an original designing procedure of fuzzy rule-based prediction systems (FRBPSs) for accurate and transparent energy consumption prediction in residential buildings. The proposed FRBPSs are characterized by a genetically optimized accuracy–interpretability trade-off. The trade-off optimization is carried out by means of multi-objective evolutionary optimization algorithms—in particular, by our generalization of the well-known strength Pareto evolutionary algorithm 2 (SPEA2). The proposed FRBPSs’ designing procedure is our original extension and generalization (for regression problems operating on continuous outputs) of an approach to designing fuzzy rule-based classifiers (FRBCs) we developed earlier and published in 2020 in this journal. FRBCs operate on discrete outputs, i.e., class labels. The experimental contribution of this work includes designing the collection of FRBPSs for residential building energy consumption prediction using the data set published in 2024 and available from Kaggle Database Repository. Moreover, the comparison with 20 available alternative approaches is carried out, demonstrating that our approach significantly outperforms alternative methods in terms of interpretability and transparency of the energy consumption predictions made while remaining comparable or slightly superior in terms of the accuracy of those predictions. Full article
(This article belongs to the Special Issue Energy Consumption in the EU Countries: 3rd Edition)
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21 pages, 4130 KiB  
Article
Frequency-Dependent Grounding Impedance of a Pair of Hemispherical Electrodes: Inductive or Capacitive Behavior?
by José Brandão Faria, João Pereira Fernandes, Vitor Maló Machado and Maria Eduarda Pedro
Energies 2024, 17(13), 3206; https://doi.org/10.3390/en17133206 - 29 Jun 2024
Cited by 4 | Viewed by 981
Abstract
This article is the authors’ last contribution to a trilogy of research papers submitted to Energies’ Special Issue on Electromagnetic Field Computation, aimed at the theoretical analysis and numerical computation of the frequency-dependent complex impedance of hemispherical electrodes. In this work, we consider [...] Read more.
This article is the authors’ last contribution to a trilogy of research papers submitted to Energies’ Special Issue on Electromagnetic Field Computation, aimed at the theoretical analysis and numerical computation of the frequency-dependent complex impedance of hemispherical electrodes. In this work, we consider a pair of distant identical hemispherical electrodes buried in the ground, whose constitutive parameters (conductivity and permittivity) are assigned diverse values. Simulation experiments carried out using a full-wave finite element method, considering different combinations of the earth’s constitutive parameters, reveal that the grounding impedance of the electrode system can exhibit surprisingly varied frequency behavior. For frequencies close to zero, the impedance can start out inductive or capacitive, then go through a number of resonant transitions between inductive and capacitive states, finally tending towards purely resistive behavior. The results are interpreted using theoretical approximations valid for low- and high-frequency regimes. Full article
(This article belongs to the Special Issue Electromagnetic Field Computation for Electrical Engineering Devices)
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22 pages, 8395 KiB  
Article
Design of Battery Energy Storage System Torsional Damper for a Microgrid with Wind Generators Using Artificial Neural Network
by Kuei-Yen Lee and Yuan-Yih Hsu
Energies 2024, 17(13), 3208; https://doi.org/10.3390/en17133208 - 29 Jun 2024
Cited by 1 | Viewed by 889
Abstract
Ancillary frequency controllers such as droop controllers are beneficial for frequency regulation of a microgrid with high penetration of wind generators. However, the use of such ancillary frequency controllers may cause torsional oscillation in the doubly fed induction generator (DFIG). In this paper, [...] Read more.
Ancillary frequency controllers such as droop controllers are beneficial for frequency regulation of a microgrid with high penetration of wind generators. However, the use of such ancillary frequency controllers may cause torsional oscillation in the doubly fed induction generator (DFIG). In this paper, a supplementary torsional damper in a battery energy storage system (BESS) is designed to improve the damping ratio for the DFIG torsional mode. Since the optimal damper gain depends on system variables such as the number of diesel generators, the number of wind generators, and BESS droop gain, an artificial neural network (ANN) is trained using these system variables as inputs and the desired BESS damper gain as the output. After the ANN has been trained with the training patterns, it can provide the desired BESS damper gain in an accurate and efficient manner. The effectiveness of the proposed ANN approach for BESS damper design is demonstrated by MATLAB/SIMULINK R2022b simulations. Full article
(This article belongs to the Special Issue Advanced Control Technology of Integrated Wind and Wave Energy Conversion System)
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23 pages, 4523 KiB  
Article
Parameter Estimation and Preliminary Fault Diagnosis for Photovoltaic Modules Using a Three-Diode Model
by Chao-Ming Huang, Shin-Ju Chen, Sung-Pei Yang, Yann-Chang Huang and Pao-Yuan Huang
Energies 2024, 17(13), 3214; https://doi.org/10.3390/en17133214 - 29 Jun 2024
Viewed by 1045
Abstract
Accurate estimation of photovoltaic (PV) power generation can ensure the stability of regional voltage control, provide a smooth PV output voltage and reduce the impact on power systems with many PV units. The internal parameters of solar cells that affect their PV power [...] Read more.
Accurate estimation of photovoltaic (PV) power generation can ensure the stability of regional voltage control, provide a smooth PV output voltage and reduce the impact on power systems with many PV units. The internal parameters of solar cells that affect their PV power output may change over a period of operation and must be re-estimated to produce a power output close to the actual value. To accurately estimate the power output for PV modules, a three-diode model is used to simulate the PV power generation. The three-diode model is more accurate but more complex than single-diode and two-diode models. Different from the traditional methods, the 9 parameters of the three-diode model are transformed into 16 parameters to further provide more refined estimates. To accurately estimate the 16 parameters in the model, an optimization tool that combines enhanced swarm intelligence (ESI) algorithms and the dynamic crowing distance (DCD) index is used based on actual historical PV power data and the associated weather information. When the 16 parameters for a three-diode model are accurately estimated, the I–V (current-voltage) curves for different solar irradiances are plotted, and the possible failures of PV modules can be predicted at an early stage. The proposed method is verified using a 200 kWp PV power generation system. Three different diode models that are optimized using different ESI algorithms are compared for different weather conditions. The results affirm the reliability of the proposed ESI algorithms and the value of creating more refined estimation models with more parameters. Preliminary fault diagnosis results based on the differences between the actual and estimated I–V curves are provided to operators for early maintenance reference. Full article
(This article belongs to the Section A2: Solar Energy and Photovoltaic Systems)
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21 pages, 1330 KiB  
Review
Recent Developments in Hydrocyclone Technology for Oil-in-Water Separation from Produced Water
by Okwunna Maryjane Ekechukwu, Taimoor Asim and Haval Kukha Hawez
Energies 2024, 17(13), 3181; https://doi.org/10.3390/en17133181 - 28 Jun 2024
Cited by 2 | Viewed by 3879
Abstract
The treatment of produced water is a major challenge faced by oil and gas industries worldwide. As a result of the increase in industrial activities, the generation of produced water has increased significantly. The most commonly used method for produced water oil–water separation [...] Read more.
The treatment of produced water is a major challenge faced by oil and gas industries worldwide. As a result of the increase in industrial activities, the generation of produced water has increased significantly. The most commonly used method for produced water oil–water separation is de-oiling hydrocyclone technology due to its simple construction, compact design, easy maintenance, and high efficiency. A wide breadth of scientific research studies has been carried out on performance evaluation, design optimisation, geometric parametrisation, external interventions, etc., to enhance the performance of hydrocyclones. These studies mostly rely on either experimental data obtained from the field, in laboratories under a controlled environment, or the application of numerical techniques for oil-in-water separation. Considering the extensive research studies published on hydrocyclone technology, this study aims to provide a comprehensive review of recent technological advancements in hydrocyclone technology in order to identify key areas where scientific research efforts should be concentrated. This will help make well-informed decisions for strategic investments in this wide area of research. Furthermore, it will widen the scope of applicability of hydrocyclones in the industrial sector. Full article
(This article belongs to the Section B: Energy and Environment)
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19 pages, 8392 KiB  
Article
Pathways to the Large-Scale Adoption of Residential Photovoltaics in Saudi Arabia
by Abeer Alshehri, Patrick James and AbuBakr Bahaj
Energies 2024, 17(13), 3180; https://doi.org/10.3390/en17133180 - 28 Jun 2024
Cited by 1 | Viewed by 1261
Abstract
This survey of predominantly middle–high-income owner-occupier households in the Kingdom of Saudi Arabia (KSA) assessed household perspectives to residential photovoltaics (PVs) (n = 268). Higher-income households were statistically more likely to (i) accept financial payback times of more than 12 months for the [...] Read more.
This survey of predominantly middle–high-income owner-occupier households in the Kingdom of Saudi Arabia (KSA) assessed household perspectives to residential photovoltaics (PVs) (n = 268). Higher-income households were statistically more likely to (i) accept financial payback times of more than 12 months for the CAPEX cost of a PV system, and (ii) be prepared to contribute up to SAR 10,000 (USD 2666) towards the CAPEX cost of a system. A multiple logistic regression analysis indicated that a high household education level and the dwelling tenure (owner) are key variables that positively influence PV acceptability. Median apartment and villa households in this survey had annual electricity demands of 22,969 kWh and 48,356 kWh, respectively. The available roof area per apartment and villa was assessed, considering parapet shading and roof furniture limitations (the presence of AC units, etc.), at 20 m2 and 75 m2, respectively. This would accommodate either a 4 kWp apartment system or a 10 kWp villa system mounted horizontally. Time-of-use tariffs or grant subsidies towards the cost of a PV system will be required to enable the surveyed households to meet their stated economic conditions for purchasing a PV system. This indicates that PV policies in KSA will need to be adapted to encourage the uptake of PVs. Full article
(This article belongs to the Special Issue Low-Carbon Integrated Energy System with Renewable Generations: Characterization, Modelling, and Optimization)
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35 pages, 2028 KiB  
Review
Control and Stability of Grid-Forming Inverters: A Comprehensive Review
by Marzie Mirmohammad and Sahar Pirooz Azad
Energies 2024, 17(13), 3186; https://doi.org/10.3390/en17133186 - 28 Jun 2024
Cited by 7 | Viewed by 4331
Abstract
The large integration of inverter-based resources will significantly alter grid dynamics, leading to pronounced stability challenges due to fundamental disparities between inverter-based and traditional energy systems. While grid-following inverters (GFLIs) dominate current inverter configurations, their increased penetration into the grid can result in [...] Read more.
The large integration of inverter-based resources will significantly alter grid dynamics, leading to pronounced stability challenges due to fundamental disparities between inverter-based and traditional energy systems. While grid-following inverters (GFLIs) dominate current inverter configurations, their increased penetration into the grid can result in major stability issues. In contrast, grid-forming inverters (GFMIs) excel over GFLIs by offering features like standalone operation, frequency support, and adaptability in weak grid scenarios. GFMIs, unlike GFLIs, control the AC voltage and frequency at the common coupling point, impacting the inverter dynamic response to grid disturbances and overall stability. Despite the existing literature highlighting differences between GFLIs and GFMIs and their control strategies, a comprehensive review of GFMIs’ stability and the effects of their control schemes on grid stability is lacking. This paper provides an in-depth evaluation of GFMIs’ stability, considering various control schemes and their dynamics. It also explores different types of power system stability, introduces new stability concepts that correspond to power grids with integrated inverters, i.e., resonance and converter-driven stability, and reviews small-signal and transient stability analyses, which are the main two types of GFMI stability studied in the literature. The paper further assesses existing studies on GFMI stability, pinpointing research gaps for future investigations. Full article
(This article belongs to the Section F: Electrical Engineering)
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35 pages, 3850 KiB  
Review
Graphitic Carbon Nitride (g-C3N4) in Photocatalytic Hydrogen Production: Critical Overview and Recent Advances
by Periklis Kyriakos, Evangelos Hristoforou and George V. Belessiotis
Energies 2024, 17(13), 3159; https://doi.org/10.3390/en17133159 - 27 Jun 2024
Cited by 8 | Viewed by 3773
Abstract
Graphitic carbon Nitride (g-C3N4) is one of the most utilized graphitic materials in hydrogen (H2) production via photocatalytic water splitting. Thus, a detailed critical overview, updated with the most recent works, has been performed on the synthesis [...] Read more.
Graphitic carbon Nitride (g-C3N4) is one of the most utilized graphitic materials in hydrogen (H2) production via photocatalytic water splitting. Thus, a detailed critical overview, updated with the most recent works, has been performed on the synthesis methods, modification techniques, characterization, and mechanisms of g-C3N4 and g-C3N4-based composite materials, with the aim of clarifying the optimum course towards highly efficient hydrogen-producing photocatalysts based on this promising material. First, the synthesis methods for different morphologies of pure g-C3N4 (bulk, nanosheets, nanotubes and nanodots) are critically analyzed in detail for every step and parameter involved, with special mention regarding the modification methods of g-C3N4 (doping and composite formation). Next, the most common results of g-C3N4 characterization, regarding structural, morphological, optical, and electrical properties, are presented and analyzed. Then, a detailed critical survey of the mechanisms, using g-C3N4 and g-C3N4-based composites during photocatalytic activity, is performed with a focus on their effect on their hydrogen production capabilities via water splitting. This review aims to provide a clear image of all aspects regarding the use of g-C3N4 for photocatalysis, as well as a comprehensive guide for research targeted towards this promising graphitic material. Full article
(This article belongs to the Special Issue Advancements in Sustainable Energy Technologies: Innovations, Integration, and Impact)
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26 pages, 3368 KiB  
Review
A Review of Machine Learning Methods in Turbine Cooling Optimization
by Liang Xu, Shenglong Jin, Weiqi Ye, Yunlong Li and Jianmin Gao
Energies 2024, 17(13), 3177; https://doi.org/10.3390/en17133177 - 27 Jun 2024
Cited by 2 | Viewed by 2937
Abstract
In the current design work, turbine performance requirements are getting higher and higher, and turbine blade design needs multiple rounds of iterative optimization. Three-dimensional turbine optimization involves multiple parameters, and 3D simulation takes a long time. Machine learning methods can make full use [...] Read more.
In the current design work, turbine performance requirements are getting higher and higher, and turbine blade design needs multiple rounds of iterative optimization. Three-dimensional turbine optimization involves multiple parameters, and 3D simulation takes a long time. Machine learning methods can make full use of historically accumulated data to train high-precision data models, which can greatly reduce turbine blade performance evaluation time and improve optimization efficiency. Based on the data model, the advanced intelligent combinatorial optimization technology can effectively reduce the number of iterations, find the better model faster, and improve the optimization calculation efficiency. Based on the different cooling parts of turbine blades and machine learning, this research explores the potential of implementing different machine learning algorithms in the field of turbine cooling design. Full article
(This article belongs to the Special Issue Thermal Design, Thermodynamic Analysis, and Optimization of Aero-Engines and Gas Turbines)
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16 pages, 7104 KiB  
Article
A Full-Controlled Bidirectional Dual-Stage Interleaved Converter for Interfacing AC and DC Power Grids
by Goncalo Marques, Vitor Monteiro and Joao L. Afonso
Energies 2024, 17(13), 3169; https://doi.org/10.3390/en17133169 - 27 Jun 2024
Cited by 3 | Viewed by 1146
Abstract
Power grids are progressing, and the possibility of incorporating DC grids toward hybrid AC/DC grids is gaining increasing relevance, as several technologies available nowadays are operating natively in DC. This paper proposes a topology of a full-controlled bidirectional dual-stage interleaved converter for interfacing [...] Read more.
Power grids are progressing, and the possibility of incorporating DC grids toward hybrid AC/DC grids is gaining increasing relevance, as several technologies available nowadays are operating natively in DC. This paper proposes a topology of a full-controlled bidirectional dual-stage interleaved converter for interfacing hybrid AC/DC grids. The topology is based on a dual-stage architecture, constituted by an AC/DC converter and by a DC/DC converter, both based on interleaved power converters. On the AC side, which is connected to the main AC power grid, the proposed dual-stage architecture operates with sinusoidal current in phase or phase opposition with the voltage, meaning a bidirectional operation. In addition, it has the possibility of interfacing with other AC loads, such as domestic electrical appliances, or with an AC microgrid. The DC link, formed by the AC/DC power stage, is interfaced with a DC power grid, which provides numerous advantages, e.g., for interfacing battery electric vehicles directly charged in DC, as well as other DC loads, such as renewable energy sources. The DC/DC power stage is considered for interfacing with an energy storage system, which is capable of bidirectional power exchange with the DC grid or with the AC grid through the AC/DC power stage. A complete laboratory prototype was designed and developed, with the unified control algorithms implemented on a digital signal processor. The experimental results validated the operation of the full-controlled bidirectional dual-stage interleaved converter based on the specifications for the hybrid AC/DC grid, such as bidirectional operation, synchronization with the AC power grid, predictive current control, interleaved operation on both AC/DC and DC/DC power stages, DC-link voltage control for the DC grid, as well as the operation with different power levels. Full article
(This article belongs to the Special Issue Power Electronics for Smart Grids: Present and Future Perspectives II)
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14 pages, 2516 KiB  
Article
Using Urban Building Energy Models for the Development of Sustainable Island Energy Systems
by Jaime Cevallos-Sierra, Afonso Pinto Gonçalves and Carlos Santos Silva
Energies 2024, 17(13), 3135; https://doi.org/10.3390/en17133135 - 26 Jun 2024
Cited by 2 | Viewed by 1793
Abstract
This study evaluates the use of City Energy Analyst, an urban building energy modelling tool, to design zero-carbon energy communities in low-industry isolated island settings. The research aims to test the effectiveness of the software during the development of sustainable energy systems in [...] Read more.
This study evaluates the use of City Energy Analyst, an urban building energy modelling tool, to design zero-carbon energy communities in low-industry isolated island settings. The research aims to test the effectiveness of the software during the development of sustainable energy systems in isolated microgrids and compares it with the widely used tool EnergyPLAN. The goal of the study focused on making a community self-sustainable, considering the rooftop area available in the populated settlements to install photovoltaic systems and distributed storage capacity. With this purpose in mind, the evaluated tool estimated the energy consumption of each building and the respective total annual consumption of Corvo Island, a location that is naturally isolated and dependent on fossil fuels. The results demonstrated that City Energy Analyst is an innovative tool to estimate energy consumption and potential energy generation of photovoltaic systems in a remote location, providing additional features to a traditional model and motivating further development of the associated plug-in. However, it requires initial time-consuming efforts to build a reliable model. As a complement, EnergyPLAN can be used to enhance the design, with the integration of the local existing and potential generation sources and to confirm the stability of the overall energy system. This tool introduced additional wind capacity and centralized storage into the model, testing the balance of the system. Therefore, the study proposes a framework combining the strengths of both tools to measure island energy systems, as they can complement each other, to build a strong analysis model. Full article
(This article belongs to the Collection Feature Paper Collection: Energy and Buildings)
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15 pages, 2165 KiB  
Article
Optimizing Biomass Supply Chains to Power Plants under Ecological and Social Restrictions: Case Study from Poland
by Jan Banaś, Katarzyna Utnik-Banaś and Stanisław Zięba
Energies 2024, 17(13), 3136; https://doi.org/10.3390/en17133136 - 26 Jun 2024
Cited by 1 | Viewed by 1496
Abstract
The growing demand for social and regulatory forest ecosystem services can significantly modify the availability and cost of biomass for energy purposes. This article presents a model for optimizing biomass supply chains using a linear programming framework integrated with a geographic information system [...] Read more.
The growing demand for social and regulatory forest ecosystem services can significantly modify the availability and cost of biomass for energy purposes. This article presents a model for optimizing biomass supply chains using a linear programming framework integrated with a geographic information system (GIS). Based on a given type of biomass resource, its calorific value, price, distance from the power plant, and transportation costs, the model identifies the optimal source of biomass, allowing it to cover the demand for the required total energy value with the lowest possible costs. The case study includes the Połaniec power plant in southeastern Poland and potential sources of forest biomass and agricultural straw within 100 km of the plant. The impact of constraints on the availability and cost of biomass was analyzed in the following scenarios: (1) all forest and agriculture biomass is available, (2) forest area in Natura 2000 network is excluded, and (3) firewood and forests with dominated ecological and social function are excluded. Unit costs of biomass varied depending on biomass availability and energy demands. The lowest unit costs of biomass (3.19 EUR/MJ) were for energy demand at the level of 1 TJ yearly for all kinds of biomass and the highest (4.91 EUR/MJ) for ecological and social constraints and energy demand 4 TJ. As energy demand increased, unit costs increased, and the ability to meet this demand with just one type of biomass decreased. The energy biomass sector can utilize the model to benefit both biomass producers and their final buyers. Full article
(This article belongs to the Special Issue Sustainable Biomass Energy Production and Utilization)
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27 pages, 1933 KiB  
Review
Solar Radiation Forecasting: A Systematic Meta-Review of Current Methods and Emerging Trends
by Ewa Chodakowska, Joanicjusz Nazarko, Łukasz Nazarko and Hesham S. Rabayah
Energies 2024, 17(13), 3156; https://doi.org/10.3390/en17133156 - 26 Jun 2024
Cited by 9 | Viewed by 4148
Abstract
Effective solar forecasting has become a critical topic in the scholarly literature in recent years due to the rapid growth of photovoltaic energy production worldwide and the inherent variability of this source of energy. The need to optimise energy systems, ensure power continuity, [...] Read more.
Effective solar forecasting has become a critical topic in the scholarly literature in recent years due to the rapid growth of photovoltaic energy production worldwide and the inherent variability of this source of energy. The need to optimise energy systems, ensure power continuity, and balance energy supply and demand is driving the continuous development of forecasting methods and approaches based on meteorological data or photovoltaic plant characteristics. This article presents the results of a meta-review of the solar forecasting literature, including the current state of knowledge and methodological discussion. It presents a comprehensive set of forecasting methods, evaluates current classifications, and proposes a new synthetic typology. The article emphasises the increasing role of artificial intelligence (AI) and machine learning (ML) techniques in improving forecast accuracy, alongside traditional statistical and physical models. It explores the challenges of hybrid and ensemble models, which combine multiple forecasting approaches to enhance performance. The paper addresses emerging trends in solar forecasting research, such as the integration of big data and advanced computational tools. Additionally, from a methodological perspective, the article outlines a rigorous approach to the meta-review research procedure, addresses the scientific challenges associated with conducting bibliometric research, and highlights best practices and principles. The article’s relevance consists of providing up-to-date knowledge on solar forecasting, along with insights on emerging trends, future research directions, and anticipating implications for theory and practice. Full article
(This article belongs to the Special Issue Simulation Modelling and Analysis of a Renewable Energy System, Volume II)
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27 pages, 5680 KiB  
Article
Comparative Analysis of Machine Learning Techniques in Predicting Wind Power Generation: A Case Study of 2018–2021 Data from Guatemala
by Berny Carrera and Kwanho Kim
Energies 2024, 17(13), 3158; https://doi.org/10.3390/en17133158 - 26 Jun 2024
Cited by 2 | Viewed by 1809
Abstract
The accurate forecasting of wind power has become a crucial task in renewable energy due to its inherent variability and uncertainty. This study addresses the challenge of predicting wind power generation without meteorological data by utilizing machine learning (ML) techniques on data from [...] Read more.
The accurate forecasting of wind power has become a crucial task in renewable energy due to its inherent variability and uncertainty. This study addresses the challenge of predicting wind power generation without meteorological data by utilizing machine learning (ML) techniques on data from 2018 to 2021 from three wind farms in Guatemala. Various machine learning models, including Gated Recurrent Unit (GRU) and Long Short-Term Memory (LSTM), Bidirectional Long Short-Term Memory (BiLSTM), Bagging, and Extreme Gradient Boosting (XGBoost), were evaluated to determine their effectiveness. The performance of these models was assessed using Root Mean Squared Error (RMSE) and Mean Absolute Error (MAE) metrics. Time series cross-validation was employed to validate the models, with GRU, LSTM, and BiLSTM showing the lowest RMSE and MAE. Furthermore, the Diebold–Mariano (DM) test and Bayesian model comparison were used for pairwise comparisons, confirming the robustness and accuracy of the top-performing models. The results highlight the superior accuracy and robustness of advanced neural network architectures in capturing the complex temporal dependencies in wind power data, making them the most reliable models for precise forecasting. These findings provide critical insights for enhancing grid management and operational planning in the renewable energy sector. Full article
(This article belongs to the Section A3: Wind, Wave and Tidal Energy)
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43 pages, 1420 KiB  
Review
Commercial Small-Scale Horizontal and Vertical Wind Turbines: A Comprehensive Review of Geometry, Materials, Costs and Performance
by Antonio Rosato, Achille Perrotta and Luigi Maffei
Energies 2024, 17(13), 3125; https://doi.org/10.3390/en17133125 - 25 Jun 2024
Cited by 7 | Viewed by 2974
Abstract
The effective exploitation of renewable energy sources is one of the most effective solutions to counter the energy, environmental and economic problems associated with the use of fossil fuels. Small-scale wind turbines (converting wind energy into electric energy with a power output lower [...] Read more.
The effective exploitation of renewable energy sources is one of the most effective solutions to counter the energy, environmental and economic problems associated with the use of fossil fuels. Small-scale wind turbines (converting wind energy into electric energy with a power output lower than 50 kW) have received tremendous attention over the past few decades thanks to their reduced environmental impact, high efficiency, low maintenance cost, high reliability, wide wind operation range, self-starting capability at low wind speed, limited installation space, reduced dependence on grid-connected power and long transmission lines, low capital costs, as well as the possibility to be installed in some urban settings. However, there are significant challenges and drawbacks associated with this technology from many different perspectives, including the significant discrepancy between theoretical performance data provided by the manufacturers and real field operation, that need to be investigated in greater depth in order to enable a more widespread deployment of small-scale wind turbines. In this review, a complete and updated list of more than 200 commercially available small-scale horizontal and vertical wind turbine models is provided and analysed, detailing the corresponding characteristics in terms of the number and material of blades, start-up wind speed, cut-in wind speed, cut-out wind speed, survival wind speed, maximum power, noise level, rotor diameter, turbine length, tower height, and specific capital cost. In addition, several scientific papers focusing on the experimental assessment of field performance of commercially available small-scale horizontal and vertical wind turbines have been reviewed and the corresponding measured data have been compared with the rated performance derived from the manufacturers’ datasheets in order to underline the discrepancies. This review represents an opportunity for the scientific community to have a clear and up-to-date picture of small-scale horizontal as well as vertical wind turbines on the market today, with a precise summary of their geometric, performance, and economic characteristics, which can enable a more accurate and informed choice of the wind turbine to be used depending on the application. It also describes the differences between theoretical and in-situ performance, emphasizing the need for further experimental research and highlighting the direction in which future studies should be directed for more efficient design and use of building-integrated small-scale wind turbines. Full article
(This article belongs to the Section A3: Wind, Wave and Tidal Energy)
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14 pages, 973 KiB  
Article
Modeling of a Biomass Cogeneration Plant from a Gasification Process
by Filipe Neves, Armando A. Soares and Abel Rouboa
Energies 2024, 17(13), 3127; https://doi.org/10.3390/en17133127 - 25 Jun 2024
Cited by 1 | Viewed by 1868
Abstract
In recent decades, growing energy demand, coupled with concerns about climate change, has led to the exploration of sustainable energy sources. Among these, biomass gasification stands out as a promising method for generating heat and power. This research delves into the potential impact [...] Read more.
In recent decades, growing energy demand, coupled with concerns about climate change, has led to the exploration of sustainable energy sources. Among these, biomass gasification stands out as a promising method for generating heat and power. This research delves into the potential impact of biomass gasification within the global energy landscape, focusing particularly on its application in cogeneration plants. Utilizing Aspen Plus software V10, this study undertook the modeling and optimization of a biomass cogeneration plant. Through simulation, it was found that a biomass flow rate of 5 kg/s yielded 6.172 MW of power output. Additionally, the study revealed several key factors that influence power generation: increasing biomass and airflow rates, increasing gasification temperature, and reducing water flow rate. By doubling the biomass flow rate to 10 kg/s and increasing the temperature to 800 °C, power generation increases by 41.75%. Moreover, the study demonstrates that Portuguese municipal waste is an efficient source of energy production, with higher cold gas and overall efficiencies compared to forest and vine-pruning residues. Full article
(This article belongs to the Section A4: Bio-Energy)
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40 pages, 5502 KiB  
Review
Technological Elements behind the Renewable Energy Community: Current Status, Existing Gap, Necessity, and Future Perspective—Overview
by Shoaib Ahmed, Amjad Ali, Alessandro Ciocia and Antonio D’Angola
Energies 2024, 17(13), 3100; https://doi.org/10.3390/en17133100 - 24 Jun 2024
Cited by 8 | Viewed by 3033
Abstract
The Renewable Energy Community (REC) in Europe promotes renewable energy sources (RESs), offering social, economic, and environmental benefits. This new entity could alter consumer energy relationships, requiring self-consumption, energy sharing, and full utilization of RESs. Modernizing energy systems within the REC requires addressing [...] Read more.
The Renewable Energy Community (REC) in Europe promotes renewable energy sources (RESs), offering social, economic, and environmental benefits. This new entity could alter consumer energy relationships, requiring self-consumption, energy sharing, and full utilization of RESs. Modernizing energy systems within the REC requires addressing self-consumption, energy sharing, demand response, and energy management system initiatives. The paper discusses the role of decentralized energy systems, the scenarios of the REC concept and key aspects, and activities involving energy generation, energy consumption, energy storage systems, energy sharing, and EV technologies. Moreover, the present work highlights the research gap in the existing literature and the necessity of addressing the technological elements. It also highlights that there is no uniform architecture or model for the REC, like in the case of microgrids. Additionally, the present work emphasizes the role and importance of technological elements in RECs, suggesting future recommendations for EMS, DSM, data monitoring and analytics, communication systems, and the software or tools to ensure reliability, efficiency, economic, and environmental measures. The authors also highlight the crucial role of policymakers and relevant policies, which could help in implementing these technological elements and show the importance of the RECs for a sustainable energy shift and transition. Full article
(This article belongs to the Section C: Energy Economics and Policy)
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41 pages, 6824 KiB  
Review
Green Hydrogen Energy Systems: A Review on Their Contribution to a Renewable Energy System
by Julián Gómez and Rui Castro
Energies 2024, 17(13), 3110; https://doi.org/10.3390/en17133110 - 24 Jun 2024
Cited by 13 | Viewed by 4996
Abstract
Accelerating the transition to a cleaner global energy system is essential for tackling the climate crisis, and green hydrogen energy systems hold significant promise for integrating renewable energy sources. This paper offers a thorough evaluation of green hydrogen’s potential as a groundbreaking alternative [...] Read more.
Accelerating the transition to a cleaner global energy system is essential for tackling the climate crisis, and green hydrogen energy systems hold significant promise for integrating renewable energy sources. This paper offers a thorough evaluation of green hydrogen’s potential as a groundbreaking alternative to achieve near-zero greenhouse gas (GHG) emissions within a renewable energy framework. The paper explores current technological options and assesses the industry’s present status alongside future challenges. It also includes an economic analysis to gauge the feasibility of integrating green hydrogen, providing a critical review of the current and future expectations for the levelized cost of hydrogen (LCOH). Depending on the geographic location and the technology employed, the LCOH for green hydrogen can range from as low as EUR 1.12/kg to as high as EUR 16.06/kg. Nonetheless, the findings suggest that green hydrogen could play a crucial role in reducing GHG emissions, particularly in hard-to-decarbonize sectors. A target LCOH of approximately EUR 1/kg by 2050 seems attainable, in some geographies. However, there are still significant hurdles to overcome before green hydrogen can become a cost-competitive alternative. Key challenges include the need for further technological advancements and the establishment of hydrogen policies to achieve cost reductions in electrolyzers, which are vital for green hydrogen production. Full article
(This article belongs to the Special Issue Simulation Modelling and Analysis of a Renewable Energy System, Volume II)
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23 pages, 2765 KiB  
Article
A SWOT Analysis of the Green Hydrogen Market
by Francisco L. D. Simões and Diogo M. F. Santos
Energies 2024, 17(13), 3114; https://doi.org/10.3390/en17133114 - 24 Jun 2024
Cited by 4 | Viewed by 3799
Abstract
Since the Industrial Revolution, humanity has heavily depended on fossil fuels. Recognizing the negative environmental impacts of the unmoderated consumption of fossil fuels, including global warming and consequent climate change, new plans and initiatives have been established to implement renewable and sustainable energy [...] Read more.
Since the Industrial Revolution, humanity has heavily depended on fossil fuels. Recognizing the negative environmental impacts of the unmoderated consumption of fossil fuels, including global warming and consequent climate change, new plans and initiatives have been established to implement renewable and sustainable energy sources worldwide. This has led to a rapid increase in the installed solar and wind energy capacity. However, considering the fluctuating nature of these renewable energy sources, green hydrogen has been proposed as a suitable energy carrier to improve the efficiency of energy production and storage. Thus, green hydrogen, produced by water electrolysis using renewable electricity, is a promising solution for the future energy market. Moreover, it has the potential to be used for the decarbonization of the heavy industry and transportation sectors. Research and development (R&D) on green hydrogen has grown considerably over the past few decades, aiming to maximize production and expand its market share. The present work uses a SWOT (strengths, weaknesses, opportunities, and threats) analysis to evaluate the current status of the green hydrogen market. The external and internal factors that affect its market position are assessed. The results show that green hydrogen is on the right track to becoming a competitive alternative to fossil fuels soon. Supported by environmental benefits, government incentives, and carbon taxes, roadmaps to position green hydrogen on the energy map have been outlined. Nevertheless, increased investments are required for further R&D, as costs must be reduced and policies enforced. These measures will gradually decrease global dependency on fossil fuels and ensure that roadmaps are followed through. Full article
(This article belongs to the Special Issue Element 1 for Sustainable Decarbonization and Net-Zero Economy: Progress in Generation, Storage, Distribution and End-Use Technologies)
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16 pages, 5933 KiB  
Article
Learning Flame Evolution Operator under Hybrid Darrieus Landau and Diffusive Thermal Instability
by Rixin Yu, Erdzan Hodzic and Karl-Johan Nogenmyr
Energies 2024, 17(13), 3097; https://doi.org/10.3390/en17133097 - 23 Jun 2024
Cited by 1 | Viewed by 1240
Abstract
Recent advancements in the integration of artificial intelligence (AI) and machine learning (ML) with physical sciences have led to significant progress in addressing complex phenomena governed by nonlinear partial differential equations (PDEs). This paper explores the application of novel operator learning methodologies to [...] Read more.
Recent advancements in the integration of artificial intelligence (AI) and machine learning (ML) with physical sciences have led to significant progress in addressing complex phenomena governed by nonlinear partial differential equations (PDEs). This paper explores the application of novel operator learning methodologies to unravel the intricate dynamics of flame instability, particularly focusing on hybrid instabilities arising from the coexistence of Darrieus–Landau (DL) and Diffusive–Thermal (DT) mechanisms. Training datasets encompass a wide range of parameter configurations, enabling the learning of parametric solution advancement operators using techniques such as parametric Fourier Neural Operator (pFNO) and parametric convolutional neural networks (pCNNs). Results demonstrate the efficacy of these methods in accurately predicting short-term and long-term flame evolution across diverse parameter regimes, capturing the characteristic behaviors of pure and blended instabilities. Comparative analyses reveal pFNO as the most accurate model for learning short-term solutions, while all models exhibit robust performance in capturing the nuanced dynamics of flame evolution. This research contributes to the development of robust modeling frameworks for understanding and controlling complex physical processes governed by nonlinear PDEs. Full article
(This article belongs to the Special Issue Towards Climate Neutral Thermochemical Energy Conversion)
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21 pages, 7618 KiB  
Article
A Method for Assessing the Technical Condition of Traction Batteries Using the Metalog Family of Probability Distributions
by Jacek Caban, Arkadiusz Małek and Dariusz Kroczyński
Energies 2024, 17(13), 3096; https://doi.org/10.3390/en17133096 - 23 Jun 2024
Cited by 6 | Viewed by 1424
Abstract
The aim of the research presented in the article is to use the Metalog family of probability distributions to assess the technical condition of traction battery packs from electric and hybrid vehicles. The description of the research object, which is a battery pack [...] Read more.
The aim of the research presented in the article is to use the Metalog family of probability distributions to assess the technical condition of traction battery packs from electric and hybrid vehicles. The description of the research object, which is a battery pack from a hybrid vehicle, will be provided. Then, a system for controlled charging and discharging of individual cells in a battery pack will be reviewed. It is an essential diagnostic and research device used to determine the capacity of individual cells. The capacity values of all battery cells will then be analyzed using the Metalog probability distribution family. The use of this tool allows us to determine the Probability Density Function for the entire battery pack. Based on this, the diagnostician is able to assess the technical condition of the tested package and decide on its further fate. It can be intended for repair, employed as a stationary energy storage facility, or used for disposal. The algorithm for assessing the technical condition of traction batteries proposed by the authors can be used in all battery packs regardless of the type of cells used and their energy capacity. Full article
(This article belongs to the Special Issue Advances in Fuel Cells and Hydrogen Storage Technologies)
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33 pages, 3393 KiB  
Review
Global Review on Environmental Impacts of Onshore Wind Energy in the Field of Tension between Human Societies and Natural Systems
by Leon Sander, Christopher Jung and Dirk Schindler
Energies 2024, 17(13), 3098; https://doi.org/10.3390/en17133098 - 23 Jun 2024
Cited by 7 | Viewed by 5454
Abstract
Deploying onshore wind energy as a cornerstone of future global energy systems challenges societies and decision-makers worldwide. Expanding wind energy should contribute to a more sustainable electricity generation without harnessing humans and their environment. Opponents often highlight the negative environmental impacts of wind [...] Read more.
Deploying onshore wind energy as a cornerstone of future global energy systems challenges societies and decision-makers worldwide. Expanding wind energy should contribute to a more sustainable electricity generation without harnessing humans and their environment. Opponents often highlight the negative environmental impacts of wind energy to impede its expansion. This study reviews 152 studies to synthesize, summarize, and discuss critically the current knowledge, research gaps, and mitigation strategies on the environmental impacts of onshore wind energy. The investigated effects comprise impacts on the abiotic and biotic environment, with birds and bats in particular, noise and visual impacts. Effects are discussed in the context of social acceptance, other energy technologies, and wind energy expansion in forests. This review illustrates that many effects are highly case-specific and must be more generalizable. Studies are biased regarding the research focus and areas, needing more standardized research methods and long-term measurements. Most studies focus on the direct mortality of birds and bats at wind farms and are concentrated in Europe and North America. Knowledge gaps persist for many impact categories, and the efficacy of mitigation strategies has yet to be proven. More targeted, unbiased research is required that allows for an objective evaluation of the environmental impacts of wind energy and strategies to mitigate them. Impacts, such as those on biodiversity, need to be addressed in the context of other anthropogenic influences and the benefits of wind energy. This forms the basis for a socially acceptable, efficient, and sustainable expansion of wind energy. Full article
(This article belongs to the Special Issue Recent Development and Future Perspective of Wind Power Generation)
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20 pages, 7300 KiB  
Article
Simulation of Power Generation System with Co-Combustion of Coal and Torrefied Biomass by Flue Gas
by Chunshuo Song, Ning Guo, Fengying Ren and Xiaohan Ren
Energies 2024, 17(12), 3047; https://doi.org/10.3390/en17123047 - 20 Jun 2024
Cited by 1 | Viewed by 1467
Abstract
At present, there is a global rise in electricity consumption, leading to an accelerated depletion of natural resources due to the reliance on fossil fuels to fulfill this energy demand. Consequently, there exists a worldwide emphasis on enhancing the proportion of renewable energy [...] Read more.
At present, there is a global rise in electricity consumption, leading to an accelerated depletion of natural resources due to the reliance on fossil fuels to fulfill this energy demand. Consequently, there exists a worldwide emphasis on enhancing the proportion of renewable energy sources in electricity generation. Biomass, as a renewable energy source, presents a viable alternative to certain fossil energy sources for combustion in electricity generation. This study focuses on a 660 MW coal-fired power plant as the subject of investigation, employing Aspen Plus simulation software (V11) to replicate the operational dynamics of the plant. A model of the direct mixed combustion biomass system within the coal-fired boiler is constructed, and its accuracy is validated against operational data obtained from the power plant. Moreover, a model elucidating the direct co-combustion of biomass in a coal-fired boiler, augmented by flue gas recirculation, was developed through the integration of biomass pre-treatment and flue gas recirculation technologies. This study explores the impacts of varying biomass blending ratios and flue gas recirculation on parameters, including flue gas volume, power generation efficiency, boiler performance, water vapor content, and emissions of pollutants. These findings indicate an inverse relationship between the mixing ratio and various performance metrics as follows: power generation, boiler efficiency, as well as NOX and SO2 content, with larger mixing ratios resulting in diminished values. Furthermore, the incorporation of flue gas recirculation was observed to mitigate furnace temperatures and suppress NOX emissions. Full article
(This article belongs to the Section A4: Bio-Energy)
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23 pages, 1842 KiB  
Article
Multi-Objective Plum Tree Algorithm and Machine Learning for Heating and Cooling Load Prediction
by Adam Slowik and Dorin Moldovan
Energies 2024, 17(12), 3054; https://doi.org/10.3390/en17123054 - 20 Jun 2024
Cited by 1 | Viewed by 1359
Abstract
The prediction of heating and cooling loads using machine learning algorithms has been considered frequently in the research literature. However, many of the studies considered the default values of the hyperparameters. This manuscript addresses both the selection of the best regressor and the [...] Read more.
The prediction of heating and cooling loads using machine learning algorithms has been considered frequently in the research literature. However, many of the studies considered the default values of the hyperparameters. This manuscript addresses both the selection of the best regressor and the tuning of the hyperparameter values using a novel nature-inspired algorithm, namely, the Multi-Objective Plum Tree Algorithm. The two objectives that were optimized were the averages of the heating and cooling predictions. The three algorithms that were compared were the Extra Trees Regressor, the Gradient Boosting Regressor, and the Random Forest Regressor of the sklearn machine learning Python library. We considered five hyperparameters which were configurable for each of the three regressors. The solutions were ranked using the MOORA method. The Multi-Objective Plum Tree Algorithm returned a root mean square error value for heating equal to 0.035719 and a root mean square error for cooling equal to 0.076197. The results are comparable to the ones obtained using standard multi-objective algorithms such as the Multi-Objective Grey Wolf Optimizer, Multi-Objective Particle Swarm Optimization, and NSGA-II. The results are also performant concerning the previous studies, which considered the same experimental dataset. Full article
(This article belongs to the Section J: Thermal Management)
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50 pages, 9834 KiB  
Review
A Review of Energy-Efficient Technologies and Decarbonating Solutions for Process Heat in the Food Industry
by François Faraldo and Paul Byrne
Energies 2024, 17(12), 3051; https://doi.org/10.3390/en17123051 - 20 Jun 2024
Cited by 3 | Viewed by 3204
Abstract
Heat is involved in many processes in the food industry: drying, dissolving, centrifugation, extraction, cleaning, washing, and cooling. Heat generation encompasses nearly all processes. This review first presents two representative case studies in order to identify which processes rely on the major energy [...] Read more.
Heat is involved in many processes in the food industry: drying, dissolving, centrifugation, extraction, cleaning, washing, and cooling. Heat generation encompasses nearly all processes. This review first presents two representative case studies in order to identify which processes rely on the major energy consumption and greenhouse gas (GHG) emissions. Energy-saving and decarbonating potential solutions are explored through a thorough review of technologies employed in refrigeration, heat generation, waste heat recovery, and thermal energy storage. Information from industrial plants is collected to show their performance under real conditions. The replacement of high-GWP (global warming potential) refrigerants by natural fluids in the refrigeration sector acts to lower GHG emissions. Being the greatest consumers, the heat generation technologies are compared using the levelized cost of heat (LCOH). This analysis shows that absorption heat transformers and high-temperature heat pumps are the most interesting technologies from the economic and decarbonation points of view, while waste heat recovery technologies present the shortest payback periods. In all sectors, energy efficiency improvements on components, storage technologies, polygeneration systems, the concept of smart industry, and the penetration of renewable energy sources appear as valuable pathways. Full article
(This article belongs to the Collection Energy Transition Towards Carbon Neutrality)
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13 pages, 5668 KiB  
Article
Markov Chain Analysis of Ship Energy Efficiency
by Yordan Garbatov, Dimitar Yalamov and Petar Georgiev
Energies 2024, 17(12), 3018; https://doi.org/10.3390/en17123018 - 19 Jun 2024
Cited by 4 | Viewed by 1063
Abstract
A formulation is presented for the assessment of the CO2 generated by ships in operation and their evolution with time, conditional on the current legislation using Markov chains. Any potential deep repair or retrofitting of the ship propulsion system or enhancement of [...] Read more.
A formulation is presented for the assessment of the CO2 generated by ships in operation and their evolution with time, conditional on the current legislation using Markov chains. Any potential deep repair or retrofitting of the ship propulsion system or enhancement of route operational characteristics during the service life are not accounted for. The Markov transition matrix is defined based on the ship operations and CO2 history of A, B, C, D, and E carbon intensity indicator (CII) rates. The transition between different CII rate states in the survey data is used to estimate the probability of transition of the analysed ships between different CII grates. Distinct transition matrices employing the progressively tightened legislation of CII are employed and analysed. In addition, the transition matrices can be fed into risk-based models that take the CII rates as input for defining the most appropriate ship energy efficiency management plan. Full article
(This article belongs to the Section B3: Carbon Emission and Utilization)
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19 pages, 1117 KiB  
Article
Economic and Energy Efficiency Analysis of the Biogas Plant Digestate Management Methods
by Mateusz Nowak, Wiktor Bojarski and Wojciech Czekała
Energies 2024, 17(12), 3021; https://doi.org/10.3390/en17123021 - 19 Jun 2024
Cited by 2 | Viewed by 1490
Abstract
The aim of this study was to conduct a comprehensive economic and energy efficiency analysis of selected digestate management methods, considering their implications on operational costs and resource management. To achieve this aim, the study focuses on a comparative assessment of different digestate [...] Read more.
The aim of this study was to conduct a comprehensive economic and energy efficiency analysis of selected digestate management methods, considering their implications on operational costs and resource management. To achieve this aim, the study focuses on a comparative assessment of different digestate management methods, including land application, mechanical separation, the composting process and pellet production. The economic analysis involves the evaluation of the initial investment, operational expenses, and potential revenue streams associated with each method. The most economical and popular solution of digestate management is direct use as fertilizer, with total costs of 1.98 EUR·Mg−1. All of the other methods involve higher digestate management costs, respectively; for separation it is 2.42 EUR·Mg−1, for composting it is 2.81 EUR·Mg−1. The process that is the most energy-intensive, but profitable, is the production of pellets from digestate, resulting in profits of 334,926 EUR·year−1. It should be noted that the other analyzed methods of digestate management also bring many environmental benefits, affecting sustainability and reducing emissions. The results of this research will contribute unique data on the feasibility of managing the digestate and its fractions. The calculations of economic and energy values for different strategies will allow for the optimization of the overall performance of the biogas plant, thus promoting a circular economy. Full article
(This article belongs to the Special Issue Biofuel Production and Bio-Waste Management)
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19 pages, 7259 KiB  
Article
Numerically Investigating the Energy-Harvesting Performance of an Oscillating Flat Plate with Leading and Trailing Flaps
by Suleiman Saleh and Chang-Hyun Sohn
Energies 2024, 17(12), 3010; https://doi.org/10.3390/en17123010 - 18 Jun 2024
Cited by 3 | Viewed by 1164
Abstract
This study investigates the power generation capability of an oscillating wing energy harvester equipped with two actively controlled flaps positioned at the leading and trailing flaps of the wing. Various parameters, including flap lengths and pitch angles for the leading flap and trailing [...] Read more.
This study investigates the power generation capability of an oscillating wing energy harvester equipped with two actively controlled flaps positioned at the leading and trailing flaps of the wing. Various parameters, including flap lengths and pitch angles for the leading flap and trailing flap, are explored through numerical simulations. The length of the main wing body ranges from 40% to 65% of the chord length, c, while the leading and trailing flaps vary accordingly, summing up to the total length of the flat plate c = 100%. The pitch angles of the two flaps are adjusted within predefined limits. The pitch angle for the leading flap varies between 25° and 55°, while the trailing flap’s angle ranges from 10° to 40° across 298 different simulation scenarios. The results indicate that employing both leading and trailing flaps enhances the power output compared to a wing with a single flap configuration. The trailing flap deflects the incoming fluid more vertically, while the leading flap increases pressure difference across the surface of the main wing body, synergistically improving overall performance. The power output occurs at a specific length percentage: a leading flap of 30%, a main wing body of 50%, and a trailing flap of 20%, with pitch angles of 50°, 85°, and 30°, respectively, increasing the output power increments by 4.39% compared to a wing with a leading flap, 4.92% compared to a wing with a trailing flap, and 28.24% compared to a single flat plate. The highest efficiency for the specified length percentages is 40.37%. Full article
(This article belongs to the Special Issue Computational Fluid Dynamics: Technologies and Applications for Renewable Energy Systems)
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24 pages, 1394 KiB  
Article
Energy Communities and Electric Mobility as a Win–Win Solution in Built Environment
by Joana Calado Martins and Manuel Duarte Pinheiro
Energies 2024, 17(12), 3011; https://doi.org/10.3390/en17123011 - 18 Jun 2024
Viewed by 1421
Abstract
Recently, there has been an increasing effort to promote energy efficiency, using renewable energies and electric mobility to achieve a more sustainable future and even carbon neutrality by 2050. This paper aims to understand if combining these technologies leads to a win–win solution. [...] Read more.
Recently, there has been an increasing effort to promote energy efficiency, using renewable energies and electric mobility to achieve a more sustainable future and even carbon neutrality by 2050. This paper aims to understand if combining these technologies leads to a win–win solution. For that, the system’s characteristics that will be used for the simulation were defined as a residential community consumption scenario with and without electric vehicles charging overnight. The simulation was completed in software, and eight scenarios were tested: high population density/low population density with/without electric mobility and hourly tariff/simple tariff. After these scenarios had been tested, the conclusion was that the low population density and hourly tariff without and with electric mobility were the best two cases economically (in terms of levelized cost of energy, net present costs, and savings) and environmentally, and the worst was high population density with hourly tariff and electric mobility. Other scenarios were then tested, including changes in the load curve, namely a commercial load curve, and changes in the load curve of electric vehicle chargers, mainly daytime charging. The conclusion was that even though the initial hypothesis did not lead to a win–win solution, with changes in the hypothesis, the integration of electric mobility in energy communities might lead to that. Full article
(This article belongs to the Special Issue Advances in Building Energy Efficiency and Sustainable Built Environment)
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17 pages, 2132 KiB  
Article
Sag and Tension Calculations for High-Voltage Overhead Line Conductors
by Marian Kampik, Paweł Kubek, Beata Krupanek and Ryszard Bogacz
Energies 2024, 17(12), 2967; https://doi.org/10.3390/en17122967 - 17 Jun 2024
Cited by 1 | Viewed by 3701
Abstract
Overhead lines are used to transmit electricity from where it is generated to the receiving stations. The correct design of an overhead line affects public safety, because it should ensure the required clearances between conductors and the ground and objects located in the [...] Read more.
Overhead lines are used to transmit electricity from where it is generated to the receiving stations. The correct design of an overhead line affects public safety, because it should ensure the required clearances between conductors and the ground and objects located in the space under the overhead line. The temperature of conductors in overhead lines depends on the load current and weather conditions, and affects the sag and tension of the conductors. Calculations of sags and tensions of overhead conductors can be performed using simplified calculation methods that do not consider insulator sets. In some situations, this approach may cause calculation errors. This article discusses algorithms for calculating overhead conductor tensions and sags in the tensioning sections of high-voltage overhead lines, accounting for and excluding insulator sets. The analysis is carried out for different lengths of tensioning sections and various thermal and mechanical states of the conductors. Full article
(This article belongs to the Special Issue Energy, Electrical and Power Engineering 2024)
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16 pages, 10279 KiB  
Article
A High-Speed Multichannel Electrochemical Impedance Spectroscopy System Using Broadband Multi-Sine Binary Perturbation for Retired Li-Ion Batteries of Electric Vehicles
by Muhammad Sheraz and Woojin Choi
Energies 2024, 17(12), 2979; https://doi.org/10.3390/en17122979 - 17 Jun 2024
Cited by 1 | Viewed by 1475
Abstract
Retired electric vehicle (EV) batteries are reused in second-life energy storage applications. However, the overall performance of repurposed energy storage systems (ESSs) is limited by the variability in the individual batteries used. Therefore, battery grading is required for the optimal performance of ESSs. [...] Read more.
Retired electric vehicle (EV) batteries are reused in second-life energy storage applications. However, the overall performance of repurposed energy storage systems (ESSs) is limited by the variability in the individual batteries used. Therefore, battery grading is required for the optimal performance of ESSs. Electrochemical impedance spectroscopy (EIS)-based evaluation of battery aging is a promising way to grade lithium-ion batteries. However, it is not practical to measure the impedance of mass-retired batteries due to their high complexity and slowness. In this paper, a broadband multi-sine binary signal (MSBS) perturbation integrated with a multichannel EIS system is presented to measure the impedance spectra for the high-speed aging evaluation of lithium-ion batteries or modules. The measurement speed is multiple times higher than that of the conventional EIS. The broadband MSBS is validated with a reference sinusoidal sweep perturbation, and the corresponding root-mean-square error (RMSE) analysis is performed. Moreover, the accuracy of the presented multichannel EIS system is validated by impedance spectra measurements of Samsung INR18650-29E batteries and compared with those measured using a commercial EIS instrument. A chi-squared error under 0.641% is obtained for all channels. The non-linearity of batteries has a significant impact on the quality of impedance spectra. Therefore, Kronig–Kramer (KK) transform validation is also performed. Full article
(This article belongs to the Special Issue Condition Monitoring and Fault Diagnosis in Power Electronics and Energy Storage Systems)
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21 pages, 6101 KiB  
Article
Closing the Loop between Waste-to-Energy Technologies: A Holistic Assessment Based on Multiple Criteria
by Christos Mertzanakis, Christos Vlachokostas, Charalampos Toufexis and Alexandra V. Michailidou
Energies 2024, 17(12), 2971; https://doi.org/10.3390/en17122971 - 17 Jun 2024
Cited by 4 | Viewed by 1335
Abstract
This paper puts forward a generic methodological framework to holistically assess WtE technologies based on the PROMETHEE approach. In addition to environmental and economic aspects, the method focuses on large-scale applicability and social preference, thus adopting economic, environmental, social, and technological criteria. Three [...] Read more.
This paper puts forward a generic methodological framework to holistically assess WtE technologies based on the PROMETHEE approach. In addition to environmental and economic aspects, the method focuses on large-scale applicability and social preference, thus adopting economic, environmental, social, and technological criteria. Three data sources are selected, namely the scientific literature, a public survey, and an experts’ opinion survey, which is a novel combination with the aim to cover public consensus, technological applicability, and to provide alternative data sources for the economic and environmental criteria, thus enriching the methodology with the input of location specific data. The demonstration of the applicability of the proposed methodology is realized at a national level for the case of Greece. Anaerobic Digestion is shown to be the most preferable choice, recognized for its cost-effectiveness and lower environmental burden to other WtE technologies (i.e., gasification, pyrolysis, incineration). When all criteria are evaluated with equal weights, anaerobic digestion greatly outperforms incineration (net flow 0.833 versus 0.1667), while incineration only becomes the most preferred choice if the social criterion is in high focus (i.e., over 63% weight). Full article
(This article belongs to the Special Issue Sustainable Management of Energy Resources, Energy Strategies and Climate Change—2nd Edition)
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